1. Field of the Invention
The present invention relates to a transflective liquid crystal display and a manufacturing method therefor.
2. Description of the Related Art
A liquid crystal display includes a liquid crystal (LC) layer interposed between two panels that are provided with field-generating electrodes. The LCD displays images by applying voltages to the field-generating electrodes to generate an electric field in the LC layer that determines orientations of LC molecules in the LC layer to adjust polarization of incident light. The light having adjusted polarization is either intercepted or allowed to pass by a polarizing film, thereby displaying images.
The liquid crystal displays are categorized as non-emissive displays, and in that respect, they do not produce any form of light. Accordingly, the LCDs utilize artificial light emitted from lamps of a backlight unit separately provided, or ambient light, as a light source. Depending on the light sources employed by the LCD, LCDs are classified as a transmissive LCD or a reflective LCD. The light source of the transmissive LCD is a backlight, and the light source of the reflective LCD is external light. The reflective type of LCD is usually applied to a small or mid-size display device. A transflective LCD has been under development. The transflective LCD uses both a backlight and external light as light sources depending on circumstances, and are usually applied to small or mid-size display devices.
The transflective LCD includes a transmissive region and a reflective region in each pixel. In the transmissive region, internal light emitted from the rear of the LCD passes through the liquid crystal layer toward front of the LCD to display images, while exterior light supplied through the front of the LCD successively passes through the LC layer and is then reflected by the reflective electrodes, and again passes through the LC layer to display images in the reflective region.
While light passes through an LC layer only once in the transmissive region, light passes through the LC layer twice in the reflective region. Due to these characteristics, difference of color tone between the transmissive region and the reflective region may occur.
To solve this problem, the LC layer may be formed to have two different thicknesses (cell gaps) between the transmissive regions and the reflective regions. For example, a plurality of organic insulator patterns are formed in the reflective regions such that cell gaps of the transmissive regions have twice the thickness as those of the reflective regions.
Manufacturing processes for a liquid crystal display are classified into a display panel manufacturing process, an alignment process, a liquid crystal cell process of filling liquid crystals between two display panels opposite each other, and a module process of attaching a driver IC, mounting back light, etc.
In the liquid crystal cell process, vacuum injection or drop injection fills the cells with liquid crystal.
With vacuum injection, a sealant with a liquid crystal inlet hole is printed around a substrate of one of two display panels. The substrates of two display panels are then aligned and assembled with each other through a hot press process with the thermal-hardening sealant. The assembled panels are put into a vacuum vessel such that the liquid crystal inlet hole of the sealer is dipped into liquid crystal. In this way, the liquid crystal is injected between two panels. Finally, the liquid crystal inlet hole is sealed such that the injected liquid crystal is contained.
With drop injection, a seal is formed around a substrate of one of two display panels in the shape of a closed curve, and then a liquid crystal is dropped onto the substrate. The substrates of two display panels are aligned, and assembled with each other by way of the seal. Finally, the seal is hardened.
As described above, the vacuum injection includes many processes such as forming a seal, aligning and assembling two display panels, putting the two display panels into a vacuum vessel, dipping into the liquid crystals, sealing the liquid crystal inlet hole, etc., such that manufacturing time and cost are increased. Accordingly, drop injection may be more economical than the vacuum injection.
However, in the transflective liquid crystal display, the organic insulator patterns formed in the reflective regions cause a height difference between regions having the organic insulator patterns and the other regions, and therefore the dripped liquid crystal in drop injection may move slowly and non-uniformly. Accordingly, the non-uniform dispersion of the liquid crystals may cause a non-uniform cell gap and vapor in liquid crystals and the liquid crystal display may appear to be stained.